package day07Exercise;

import java.util.Random;

public class VerificationCode {
    public static void main(String[] args) {
        /**
         * 需求：生成4位数字验证码（大写字母，小写字母，数字）
         */
        String code=generateVerification(6);
        System.out.println("6位验证码为："+code);

    }
    public static String generateVerification(int len){
        String code="";
        char[] chs={'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o',
                'p','q','r','s','t','u','v','w','x','y','z','A','B','C','D','E','F','G',
                'H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z',
                '0','1','2','3','4','5','6','7','8','9'};//生成验证码的字符
        Random rand=new Random();
        for (int i=0;i<len;i++) {
//            int index = (int) (Math.random() * chs.length);//字符下标索引值0-61
            int index=rand.nextInt(chs.length);//字符下标索引值
            code += chs[index];

        }
        return code;
    }
}
